In printed electronics, electronic circuits, devices and the like are formed by utilizing a printing technology. For example, a functional material (electrically conductive material) of an ink form is applied in a certain pattern onto a surface of a substrate (base) by a printing method, a transferring method or the like. In recent years, the printed electronics are an attractive technology which makes it possible to produce large-area electronic circuits and devices at lower costs without a need for an expensive large-scale production equipment such as a vacuum equipment. However, the conventional printed electronics technology requires a firing process to fire the functional material (electrically conductive material) at a temperature of 100° C. to 200° C. or higher and, therefore, is disadvantageous in that a lower-melting point base, particularly a material such as a resin film susceptible to thermal expansion and contraction, cannot be used as the base.
To cope with this, the inventors developed an electrically conductive ink (nano-ink composition, see PTL 1) which obviates the need for the firing after application thereof, and proposed an electronic circuit board production method which is capable of efficiently and stably forming an electronic circuit pattern having a sufficient electrical conduction property on a thermally-unstable flexible base such as paper or a resin film with the use of the nano-ink (Japanese Patent Application No. 2014-204612).
This electronic circuit board production method obviates the need for the firing process and, therefore, the entire production process can be performed at a temperature at which the materials such as paper and resin film are unlikely to suffer from deformation and thermal expansion and contraction which may otherwise cause permanent setting of the material shape. Further, the nano-ink composition is applied onto the base in an ordinary temperature atmosphere by a flexographic printing method or the like, and then dried to be fixed to the base at a temperature of not higher than 40° C. Therefore, an electronic circuit of a minute pattern can be highly accurately formed on the thermally-unstable flexible base.